KIM Uno /PiDP-11 plans...

[Ethan Dicks]

On Fri, Oct 23, 2015 at 9:19 AM, Jay West <jwest at classiccmp.org> wrote:
> Dave wrote...
> ------
> I think that the switches can be found, but they might be expensive.

Any of these C&K-type switches are likely to sell for $4-$6 each as
new (I've gotten fistfuls of similar ones at Hamfests for $0.75 or
less, but it's very hit-miss; not the sort of thing you could base a
product off of).

> But as Noel wrote... the problem isn't the CK switches as far as the "model
> number" on them goes.

Yes.  The bodies are very standard, but the momentaries can be more
difficult to find, even if they have SPDT on-on bodies.  The 4-digit
number on the side will tell much.  AFAIK, there are 2 types used in a
real DEC front panel, with some of the momentaries mounted facing one
way, some facing the other way.

>The problem is that CK
> switches used in these systems were custom made with a flat metal plate at
> the bottom of the handle (even though they had a standard CK part number on
> them), which is what was used to attach them to the metal reinforcement
> strip.

I don't think it's a DEC-custom clip design, but it is not C&K's most
popular mounting scheme.

> So you can find a "7301" (or whatever the model number is on these CK
> switches), but good luck finding any "7301"'s with the custom metal plate.

Essentially, yes.  7301s are easy enough to find (at the
aforementioned $5-$6 each), but not with the panel clips.

> As Noel said, a new mechanical design would need to be made.

A new mechanical design would allow for the use of a wider range of
switches that would be more available.

For paddle-type switches (with the small stub for mating with a DEC
toggle handle), what I've seen as more common have larger metal
"frame" that is also bonded into the switch stack like the panel clips
DEC used.  The frame has solder lugs that mount on the PCB next to the
signal leads, giving a bigger footprint on the PCB.  I have a few
handfuls of those, with paddles, that I picked up at Dayton and other
places.  It's the style that Bob Armstrong used with the original
FP6120 (for the SBC6120RC he later changed to simple toggle switches
with round panel holes and knurled nuts because those are far more
common).  These "framed" switches won't easily mount in a real DEC
front panel, so they don't help the person who is trying to restore a
real front panel, but they would be a good choice for a from-scratch
replica.  You still end up with over $100 in switch bodies, but that's
just the way these are.

-ethan